KR20060135747A - Electrophoretic display apparatus and driving method thereof - Google Patents

Abstract

A distribution of migration particles 5 and 6 dispersed in a closed space formed by first substrate 1 and a second substrate 2 is changed by a display electrode 7 to effect display. The migration particles 5 and 6 are migration particles of two types having different charge polarities and a substantially identical color. To the display electrode 7, a display voltage of a predetermined polarity and a display voltage of a polarity opposite to the predetermined polarity of the display voltage are alternately applied. Stable display can be effected by removing a DC component from an applied voltage.

Description

Electrophoretic display and driving method of electrophoretic display device {ELECTROPHORETIC DISPLAY APPARATUS AND DRIVING METHOD THEREOF}

The present invention relates to an electrophoretic display device and a method of driving the electrophoretic display device for displaying on the basis of the movement of the electrophoretic particles.

In recent years, due to the remarkable progress of digital technology, the amount of information that an individual can handle has increased dramatically. In this regard, development of displays as information output means has been actively carried out, and technology innovation continues with high usability displays such as high precision, low power consumption, light weight, and thinness. In particular, in recent years, easy-to-read precision displays having display quality equivalent to that of printed matter are expected. This type of display is indispensable for next generation products such as electronic paper and electronic books.

By the way, Evans et al. In U.S. Patent No. 3612758 disclose, as a candidate for such a display, a dispersion medium containing colored electrophoretic particles and a colorant between a pair of substrates, and the colored electrophoretic particles and coloring. There is proposed an electrophoretic display device which forms an image by contrast color between the dispersion mediums.

However, in such an electrophoretic display device, a problem arises that the lifetime and contrast of the display device decrease due to the inclusion of colorants such as dyes. In view of these problems, an electrophoretic display device which forms an image by contrast color between colored electrophoretic particles dispersed in a transparent dispersion medium and a colored layer disposed on a substrate without coloring the dispersion medium is disclosed in Japanese Patent Laid-Open No. 11-202804. It is proposed in the publication.

By the way, in such a conventional electrophoretic display device, since the electrophoretic particles are moved by an electric field, a DC voltage is applied to the display element at the time of display rewriting. However, when such display rewriting is repeated many times, as a result, a long time DC voltage may be applied to the display element.

In addition, when the DC voltage is applied to the display element for a long time in this manner, a space charge distribution is formed by electrons or ions in the insulating layer or the dispersion medium, and accumulates as a residual DC component. As a result, the voltage applied to the electrophoretic particles fluctuates, causing a problem of display burn-in in which a predetermined gradation optical level cannot be obtained.

[Initiation of invention]

The present invention has been accomplished in view of the above environment.

The present invention is to provide an electrophoretic display device capable of repeatedly performing a stable display.

Still another object of the present invention is to provide a method of driving the electrophoretic display device.

 According to a first aspect of the present invention, there is provided a display device including a first substrate having an airtight container, a pair of electrodes for generating an electric field in the airtight container, and charged particles held in the airtight container. The charged particles are moved by an electric field to determine the distribution of the charged particles in the sealed container and thereby display the charged particles, wherein the charged particles are composed of two types having different charging polarities and substantially the same color. A display device is provided.

More specifically, the electrophoretic display device includes a first substrate and a second substrate disposed in a predetermined space therebetween to form a closed space, and are substantially the same color having different counter electrode properties distributed in the closed space. It contains two types of electrophoretic particles (charged particles).

In addition, the electrophoretic display device of the present invention preferably includes a display electrode for changing the distribution state of the electrophoretic particles in order to perform the display, wherein the display electrode has a display voltage of a predetermined polarity and the predetermined polarity. The display voltage of and the display voltage of the predetermined polarity and the reverse polarity are alternately applied, thereby changing the distribution state of the migrating particles.

Preferably, the electrophoretic display device includes first and second reset electrodes for changing the distribution state of the electrophoretic particles in order to reset the display, and reset voltages having a predetermined polarity to the first and second reset electrodes. And a reset voltage of the predetermined polarity and a reset voltage of reverse polarity are alternately applied.

The electrophoretic display device includes a barrier rib that maintains a constant gap between the first substrate and the second substrate, display electrodes provided on the first substrate and the second substrate, and the first and the second electrodes facing the partition wall. It is preferable to include 2 reset electrodes.

Preferably, the electrophoretic display device includes the display electrode provided on one of the first and second substrates, and the first and second reset electrodes provided on the other side of the substrate.

In a preferred embodiment of the present invention, the display electrode is a common electrode, and a voltage having a predetermined polarity is a relative potential difference between the common electrode and one of the reset electrodes of the first and second reset electrodes. The display voltage which is reverse polarity with respect to the polarity voltage is the relative potential difference between the common electrode and the other reset electrode of the first reset electrode and the second reset electrode.

According to another aspect of the present invention, there is provided a electrophoretic display device comprising: a first substrate and a second substrate disposed at predetermined intervals to form a closed space; An electrophoretic display device comprising electrophoretic particles dispersed in the closed space, wherein the electrophoretic display device performs display by changing the distribution of the electrophoretic particles in the closed space, wherein the device is configured to change the distribution of the electrophoretic particles to perform display. And a display medium and a dispersion medium having a relative dielectric constant different from that of the moving particles filled in the waste space and dispersed in the dispersion medium, wherein the moving particles are moving particles having substantially the same color as two kinds of different counter electrodes. An electrophoretic display device is configured to alternately apply a display voltage having a predetermined polarity, a voltage having a predetermined polarity, and a display voltage having a reverse polarity to the display electrode.

In a preferred embodiment, the electrophoretic display device further comprises a reset electrode for changing the distribution state of the electrophoretic particles for resetting the display, wherein the display electrode and the reset electrode have a non-uniform electric field distribution therebetween. Arranged so as to be formed, and when the display is reset, an alternating voltage is applied to the display electrode.

The electrophoretic display device further includes a barrier rib that maintains a constant gap between the first substrate and the second substrate, wherein the display electrode is disposed on the first substrate or the second substrate and the reset electrode is disposed on the barrier rib. Are arranged opposite.

In a preferred embodiment of the present invention, when the relative dielectric constant of the electrophoretic particles is greater than the relative dielectric constant of the dispersion medium, the operation of moving the moving particles to a strong electric field region of the non-uniform electric field distribution is a reset operation, the electrophoretic particles When the relative dielectric constant of is smaller than the relative dielectric constant of the dispersion medium, the operation of moving the migrating particles to the weak electric field region of the nonuniform electric field distribution becomes a reset operation.

In addition, the electrophoretic apparatus preferably includes a microcapsule disposed in the space between the first substrate and the second substrate as the closed space.

According to still another aspect of the present invention, a first space and a second substrate having a waste space interposed therebetween, the electrophoretic particles having different counter-electrode properties and substantially the same color and are dispersed in a sealed container and are sealed A method of driving an electrophoretic display device, comprising: an electrode for generating an electric field in a container, wherein the distribution state of the electrophoretic particles is changed in the hermetically sealed container to perform display;

Providing a display electrode for changing the distribution of the charged particles for displaying and a first and second reset electrode for changing the distribution of the charged particles for resetting the display;

A first reset operation for resetting the display by applying a reset voltage of a predetermined polarity to the first and second reset electrodes, and a first display operation for displaying by applying a display voltage of a predetermined polarity to the display electrode; And a second reset operation for resetting the display by applying a reset voltage having a reverse polarity to that of the predetermined polarity to the first and second electrodes, and a display voltage having the predetermined polarity to the display electrode. A method of driving a display device comprising the step of repeating a second display operation for displaying by applying a display voltage of reverse polarity.

According to another aspect of the present invention, the first substrate and the second substrate disposed to have a predetermined space to form a waste space, and including the electrophoretic particles dispersed in the waste space, the distribution state of the A drive driving method of an electrophoretic display device which performs display by changing in the closed space,

A display electrode for varying the distribution of the migrating particles for performing the display, a reset electrode for changing the display in which the migrating particles are rewritten to reset the display, and the migrating particles are dispersed and different from the phoretic particles. Providing a dispersion medium having a relative dielectric constant;

A process using two kinds of electrophoretic particles having different counter electrode properties and having substantially the same color as the electrophoretic particles,

Disposing the display electrode and the reset electrode such that a non-uniform electric field distribution is formed therebetween;

A first display operation for displaying by applying a display voltage of a predetermined polarity to the display electrode, a reset operation for performing a reset by applying an alternating voltage to the display electrode, and a display voltage of the predetermined polarity to the display electrode; Repeating the second display operation of displaying by applying a display voltage of reverse polarity

It provides a method of driving an electrophoretic display comprising a.

According to the present invention, since two kinds of charged particles having substantially the same color as different charged particles are used as the moving particles, the electrophoretic display device can be driven by an alternating voltage. Further, even when the display or the display rewriting is repeatedly performed, the display voltage having a predetermined polarity and the display electrode having a reverse polarity with respect to the predetermined polarity are alternated with respect to the display electrode for displaying by changing the distribution of the electrophoretic particles. By application of, it is possible to prevent the accumulation of components of the residual direct current and to perform stable display repeatedly.

These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention given in conjunction with the accompanying drawings.

1 (a) and 1 (b) are schematic configuration diagrams of an electrophoretic display element provided in an electrophoretic display device according to a first embodiment of the present invention;

2 (a) and 2 (b) are schematic diagrams illustrating a display operation method of the electrophoretic display elements shown in FIGS. 1 (a) and 1 (b);

3 (a) and 3 (b) are schematic configuration diagrams of an electrophoretic display element provided in an electrophoretic display device according to a second embodiment of the present invention;

4 (a) and 4 (b) are schematic diagrams for explaining a display operation method of the electrophoretic display elements shown in FIGS. 3 (a) and 3 (b);

5 (a) and 5 (b) are schematic configuration diagrams of an electrophoretic display element provided in an electrophoretic display device according to a third embodiment of the present invention;

6 (a) and 6 (b) are schematic diagrams for explaining a display operation method of the electrophoretic display elements shown in FIGS. 5 (a) and 5 (b);

7 is a schematic diagram showing a planar shape of a pixel of an electrophoretic display element according to the first embodiment of the present invention;

8 (a) and 8 (b) are schematic diagrams for explaining a driving method for driving the electrophoretic display element according to the embodiment of the present invention;

9 is a schematic diagram showing a planar shape of a pixel of an electrophoretic display element according to a third embodiment of the present invention;

10 (a) and 10 (b) are schematic diagrams for explaining a driving method for driving the electrophoretic display element according to the embodiment of the present invention;

11 (a) and 11 (b) are schematic diagrams for explaining another driving method for driving the electrophoretic display element according to the embodiment of the present invention;

<Description of the symbols for the main parts of the drawings>

1: first substrate 2: second substrate

3: dispersion medium 4: bulkhead

5, 6: Young particles 7: First electrode

8: second electrode 9: third electrode

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment for implementing this invention is described in detail, referring drawings.

1 (a) and 1 (b) show a schematic configuration of an electrophoretic display element provided in an electrophoretic display device according to a first embodiment of the present invention. 1 (a) and 1 (b), the electrophoretic display element is a second substrate 2 disposed on the display side with a predetermined distance between the first substrate 1 and the first substrate 1. It includes.

A hermetically sealed container formed by a partition wall 4 arranged to maintain a constant distance between the first substrate 1, the second substrate 2, and the first substrate 1 and the second substrate 2. In the dispersion medium 3 filled in the inside, two kinds of migrating particles (first particles 5 and second particles 6) having the same color as different counter electrodes are dispersed.

A first electrode 7 is formed on the first substrate 1, and a first reset electrode (second electrode) and a second reset electrode (third electrode) are formed along the side surface of one partition wall 4. By applying a voltage to the first electrode 7, the second electrode 8, and the third electrode 9, a pixel formed of the first substrate 1a, the second substrate 2, and the partition wall 4 is applied. An electric field is formed in the corresponding closed space. By this electric field, two kinds of the electrophoretic particles 5 and 6 are selectively moved to display. The first electrode 7 has a larger size (plane area) than the second electrode 8 and the third electrode 9 and is colored in a predetermined color.

By the way, in the electrophoretic display element having such a configuration, a first display operation for applying a display voltage having a predetermined polarity to the first electrode 7 and displaying or rewriting the display and a first display operation for the first electrode 7 are performed. The second display operation for displaying or rewriting the display by applying a predetermined display voltage of reverse polarity is alternately performed.

In addition, before the first display operation and the second display operation, the first reset operation, the first reset operation and the reverse polarity of applying a reset voltage of a predetermined polarity to the second and third electrodes 8 and 9 and resetting the display are reversed. The second reset operation of resetting the display by applying a predetermined reset voltage of? Is alternately repeatedly performed.

Next, the display operation of the electrophoretic display element will be described. In the present embodiment, the first particles 5 are positively charged black particles, and the second particles 6 are negatively charged black particles, and the first electrode 7 is colored white.

A first display operation will be described with reference to FIGS. 1A and 1B.

First, as shown in Fig. 1A, by applying 0V to the first electrode 7, -10V to the second electrode 8 and + 10V to the third electrode 9 as a reset voltage of a predetermined polarity, The positively charged first particles 5 are moved to the second electrode side, and the negatively charged second particles 6 are moved to the third electrode side to reset the particle position (first reset operation). At this time, since the first and second particles 5 and 6 do not exist above the first electrode 7, the first electrode 7 is exposed and becomes white.

Next, as shown in Fig. 1 (b), + 10V is applied to the first electrode 7 as a display voltage having a predetermined polarity, and 0V and the third electrode 9 are applied to the second electrode 8, respectively. By applying 0V to the negative electrode, the negatively charged second particles 6 are moved onto the first electrode. At this time, since the first electrode 7 is covered by the black second particles 6, the black display rewriting is performed. In addition, when performing display reshaping of halftones, for example, the amount of the second particles 6 to be moved to the first electrode 7 by changing the magnitude or the application time of the voltage applied to the first electrode 7. To change.

Next, the second display operation will be described with reference to Figs. 2 (a) and 2 (b).

In this case, first, as shown in Fig. 2A, 0V is applied to the first electrode 7, + 10V is applied to the second electrode 8 as the reset voltage of the first reset operation and reverse polarity, and the third electrode 9 ) By applying -10V, the positively charged first particles 5 are moved to the third electrode side and the negatively charged second particles 6 to the second electrode side to reset the particle position (second Reset operation). At this time, since the first particles and the second particles 5 and 6 do not exist, the first electrode 7 is exposed, resulting in white display.

Next, as shown in FIG. 2 (b), -10V is applied to the first electrode 7, 0V is applied to the second electrode 8, and 0V is applied to the third electrode 9 as a predetermined display voltage of reverse polarity. By application, the positively charged first particles 5 are moved onto the first electrode. At this time, since the first electrode 7 is covered by the first black particles 5, the black display is rewritten. When the display of halftones is rewritten, for example, the first particles 5 to be moved to the first electrode 7 by changing the magnitude of the voltage applied to the first electrode 7 or the application time thereof. Change the amount.

Here, although the first display operation and the second display operation are both black display (halftone) rewriting, the display voltage applied to the first electrode 7 uses a reverse polarity voltage. More specifically, by using two kinds of particles 5 and 6 having counterelectrode characteristics having the opposite polarity and the same color, when the voltages having different polarities are alternately applied to the first electrode 7, the first display operation is performed. And the second display operation can be performed alternately.

As described above, even when the display rewriting is repeated by alternately applying the voltages having different polarities to the first electrode 7 and alternately performing the first display operation and the second display operation. The effective voltage at one electrode 7 can approach zero on average. As a result, it is possible to prevent accumulation of residual DC components and to perform stable display rewriting with suppressed display burn-in.

In general, since the electrophoretic display apparatus has a memory characteristic with respect to the display state, the display holding operation may be performed after the display operation. Here, in the case where the display of the display state is continued after the display rewriting, it is not necessary to perform the above display operation, but only the display holding operation may be performed. In addition, the display holding operation is intended to maintain the position of the electrophoretic particles, and in general, only the application of a voltage of 0 V to each electrode may be performed.

As another display holding operation, for example, there is an operation of applying a minute voltage that suppresses the movement of the moving particles, or an operation of applying a pulse voltage that regularly corrects the position of the moving particles. . Since the electrophoretic display has memory characteristics, power consumption can be reduced. In addition, when the display state is continuously changed as in the video, the first display operation and the second display operation are repeated alternately.

In the present embodiment, by using the first particles and the second particles of the same color having different counter electrode properties, the same gray scale display can be performed even when a reverse polarity voltage is applied to the electrodes.

In addition, this reverse polarity voltage does not necessarily need to be a complete target voltage. In addition, as in the present embodiment, the color of the two kinds of the electrophoretic particles 5 and 6 is not particularly limited, and in addition to black, white, red, green, blue, crimson, cyan, yellow and the like can be appropriately selected. have.

Next, a second embodiment of the present invention will be described.

3 (a) and 3 (b) show a schematic configuration of an electrophoretic display element provided in the electrophoretic display device according to the present embodiment. In these figures, members or means denoted by the same reference numerals shown in Figs. 1A and 1B represent the same or corresponding members or means.

In FIGS. 3A and 3B, the colored dispersion medium 41 is filled in the closed space formed by the first substrate 1, the second substrate 2, and the partition wall 3. In this embodiment, the first electrode 7 is arranged on the second substrate, the second electrode 8 and the third electrode 9 are arranged on the first substrate.

Also in this embodiment, this electrophoretic display element alternately performs the first display operation and the second display operation.

Next, the display operation of such an electrophoretic display element will be described. In the present embodiment, the first particles 5 become positively charged white particles, the second particles 6 become negatively charged white particles, and the dispersion medium 41 is colored black. The first electrode 7 is a common electrode to which the same voltage is applied to all the pixels, and a voltage of 0V is applied.

First, the first display operation will be described with reference to Figs. 3A and 3B.

First, as shown in FIG. 3 (a), −10 V is applied to the second electrode 8 and +10 V is applied to the third electrode 9 as a reset voltage having a predetermined polarity. ) Is moved to the second electrode side, and the negatively charged second particles 6 are moved to the third electrode side to reset the particle position (first reset operation). At this time, the observer on the second substrate side observes the black dispersion medium 41, and black display is performed.

Next, as shown in Fig. 3B, the second electrode is formed between the first electrode 7 and the second electrode 8, which are common electrodes, to form a potential difference corresponding to the display voltage of a predetermined polarity. By applying -10V to (8) and applying 0V to the third electrode 9, the negatively charged second particles 6 are moved onto the first electrode 7. At this time, the observer on the second substrate side observes the white second particles 6 and the white marking is rewritten. In the case of displaying the halftones, the first electrode 7 is moved to the first electrode 7 by changing the magnitude or the application time of the voltage applied to the second electrode 8 and the third electrode 9, for example. The amount of the two particles 6 is changed.

Next, the second display operation will be described with reference to Figs. 4A and 4B.

In this case, as shown in Fig. 4A, + 10V is applied to the second electrode 8 and -10V is applied to the third electrode 9 as a reset voltage which is reverse polarity to the predetermined polarity of the first reset operation. Then, the positively charged first particles 5 are moved to the third electrode side, and the negatively charged second particles 6 are moved to the second electrode side, thereby resetting the particle position (second reset operation). At this time, the observer on the second substrate side observes the black dispersion medium 41, and black display is performed.

Next, as shown in Fig. 4B, the display voltage of the first display operation is + 10V between the second electrode 8 and between the first electrode 7 and the third electrode 9, which are common electrodes. The positively charged first particles 5 are moved onto the first electrode by applying +10 V to the third electrode 9 to form a potential difference corresponding to the display voltage having a predetermined polarity and reverse polarity. At this time, the observer on the second substrate side observes the white first particles 5 and becomes a white display rewrite. In addition, when performing display reshaping of halftones, the first particles to be moved to the first electrode 7 by changing the magnitude and the application time of the voltage applied to the second electrode 8 and the third electrode 9. Change the amount of (5).

In the present embodiment, the first display operation and the second display operation are both black display (halftone) rewrites, but the voltage applied between the second and third electrodes 8 and 9 causes a reverse polarity voltage. I use it. In addition, similarly to the first embodiment described above, even when the display rewriting is repeated, the first display operation and the second display operation are performed by applying voltages of different polarities to the second and third electrodes 8 and 9. By alternately performing, the effective voltage can be approached to zero on average. As a result, stable display rewriting can be performed while preventing the accumulation of residual DC components and suppressing display burn-in.

By the way, in the said 1st and 2nd embodiment, although the case where display reorganization was performed by using electrophoretic force was demonstrated, this invention is not limited to this. In the present invention, display reorganization can be performed by using a dielectric kinetic force.

Here, the dielectrophoretic force is a force acting on the electrolytic particles which is clearly distinguished from the electrophoretic force, and assuming that the particles are spherical, it is determined by the following equation:

F = 2πr ³ ε ₁ ε ₀ ｛(ε ₂ -ε ₁ ) / (ε ₂ + 2ε ₁ )｝ ∇E ² . (One)

Where F is the dielectric kinetic force, r is the radius of the particle, ε ₀ is the dielectric constant of the vacuum, ε ₁ is the relative dielectric constant of the dispersion medium, ε ₂ : the relative dielectric constant of the particle, E is the external electric field, and ∇ is the spatial derivative.

As can be seen from Equation (1), when a non-uniform electric field is formed in a sealed container, when the relative dielectric constant of the electrophoretic particles is larger than that of the surrounding dispersion medium, the electrophoretic particles have a strong electric field. Go to. On the contrary, when the relative dielectric constant of the migrating particles is smaller than the relative dielectric constant of the surrounding dispersion medium, the migrating particles move to a region having a weak electric field.

Dielectrophoretic force also acts upon application of a DC voltage, but since electrophoretic force generally exceeds the dielectrophoretic force, the motion of the electrophoretic particles is less affected by the dielectrophoretic force.

However, when AC voltage is applied, vibrating electrophoretic force is generated at AC frequency of low frequency. However, if the frequency is increased, the movement of the migrating particles cannot be followed gradually, and the electrophoretic force is attenuated. As a result, the dielectrophoretic force predominantly acts on the electrophoretic particles.

In addition, as can be seen from equation (1), when there is no difference in the relative dielectric constant between the electrophoretic particles and the dispersion medium, the dielectric force is lost. For this reason, it is necessary for the electrophoretic particles and the dispersion medium to have different relative dielectric constants.

In addition, the predetermined nonuniform electric field (field gradient) distribution in the closed space can be formed by the difference in dielectric constant between members and the arrangement and shape of the electrode. For example, a nonuniform distribution can be formed in the closed space by disposing the electrodes so that the distance between the two electrode surfaces is not constant and has a maximum value and a minimum value. In this case, a strong ammeter region of non-uniform electric field is formed in a region where the distance between the electrode surfaces is minimum, and a weak electric field region is formed in a region where the distance between the electrode surfaces is maximum.

As can be seen from Equation (1), the direction of action of the dielectrophoretic force is determined in one direction irrespective of the counterelectrode property of the electrophoretic particles if only the relationship between the relative dielectric constant between the electrophoretic particles and the dispersion medium is determined. Therefore, by using the dielectrophoretic force, the first particles and the second particles having different counterelectrodes can be moved in the same region. The difference in relative dielectric constant between the electrophoretic particles and the dispersion medium is 5 <| ε ₂ -ε ₁ | <50 is preferable. Still more preferably, 8 <| ε ₂ -ε ₁ | <20.

Also, if the electrophoretic force is small, the response speed becomes slow. On the contrary, if the electrophoretic force is too large, the electrophoretic particles cannot move in the strong electric field region (or weak electric field region), resulting in a poor driving of the electrophoretic display device.

In addition, since the frequency of the AC voltage is not particularly limited and can be selected, the frequency of movement of the electrophoretic particles becomes higher than the frequency at which the dielectric electrophoretic force becomes dominant, and the electrode arrangement (nonuniform electric field distribution), particle size, Although it depends on the difference in the dielectric constant of a dispersion medium, the charge amount of a electrophoretic particle, etc., normally several hundred Hz or more is preferable. Also, the waveform of the AC voltage is not particularly limited, and square waves, sine waves, triangular waves, and the like can be selected.

Next, a third embodiment of the present invention will be described.

5 (a) and 5 (b) show a schematic configuration of an electrophoretic display element provided in the electrophoretic display device according to the present embodiment in order to reorganize the display by using dielectric electrophoretic force. In these drawings, the same reference numerals for the members shown in Figs. 1A and 1B indicate the same or corresponding members.

5 (a) and 5 (b), the first electrode 71 is formed on the first substrate, and the second electrode 81 is a reset electrode provided on the partition wall 3 and the partition wall 3 is formed. It is formed on the surface or inside. More specifically, the second electrode 81 is closer to the first electrode 71 as it is closer to the first substrate 1, that is, the distance between the first electrode surface and the second electrode surface is closer to the pixel side. It is formed so that it is minimum in a partition part.

By disposing the electrodes 71 and 72 so that the distance between the first electrode surface and the second electrode surface is minimum in the partition wall portion, a non-uniform electric field distribution is formed. As a result, in Fig. 5 (a), where the distance between the first electrode surface and the second electrode surface is closest, a strong ammeter region can be formed in the region indicated by A. FIG.

Next, the display operation of the electrophoretic display element of the present embodiment will be described. In the present embodiment, the first particles 5 are positively charged black particles, the second particles 6 are negatively charged black particles, and the first electrode 71 is colored white. In addition, the relationship between (relative dielectric constant of the moving particles) &gt; (dielectric constant of the dispersion medium) is satisfied, and the second electrode 81 is a common electrode to which substantially the same voltage is applied to all the pixels, and a voltage of 0 V is supplied. .

The first display operation will be described with reference to Figs. 5 (a) and 5 (b).

First, as shown in FIG. 5A, a positively charged first particle 5 and a negatively charged second particle 6 are applied by applying an AC voltage of ± 20 V to the first electrode 71. Both of them move to the strong ammeter area (area A) to thereby reset the particle position (first reset operation). At this time, the first electrode 71 is exposed to form a white display.

Next, as shown in Fig. 5 (b), by applying + 10V to the first electrode 71 as a display voltage of a predetermined polarity, the negatively charged second particles 6 are moved onto the first electrode. . At this time, since the first electrode 71 is covered by the black second particles 6, black display is obtained. When halftone display rewriting is performed, for example, the amount of the second particles 6 to be moved to the first electrode 71 by changing the magnitude or the application time of the voltage applied to the first electrode 71. By changing the

Next, the second display operation will be described with reference to Figs. 6 (a) and 6 (b).

In this case, as shown in FIG. 6A, an AC voltage of ± 20 V is applied to the first electrode 71 so that both the first particle 5 and the second particle 6 are strong ammeter areas (areas). By moving to A), the particle position is reset (second reset operation). At this time, the first electrode 71 is exposed to form a white display.

Next, as shown in Fig. 6 (b), the positively charged first particles 5 are applied to the first electrode by applying -10V to the first electrode 71 as a predetermined display voltage of reverse polarity. Move it. At this time, since the first electrode 71 is covered by the black first particles 5, black display is obtained. In addition, when performing display reshaping of halftones, for example, the first particles 5 to be moved to the first electrode 71 by changing the magnitude or the application time of the voltage applied to the first electrode 71. By changing the amount of.

Also in the present embodiment, similarly to the first and second embodiments described above, even when the display rewriting is repeated by alternately performing the first display operation and the second display operation, the first electrode 7 is reversed. Since the voltages of the polarity are alternately applied, the effective voltage can approach zero on average. As a result, it is possible to prevent the accumulation of residual DC components and to perform stable display rewriting while suppressing display burn-in.

In addition, in this embodiment, it is possible to move two kinds of particles having different counterelectrode characteristics in the same direction by performing an AC voltage reset using a dielectric electrophoretic force. As a result, the number of electrodes can be reduced as described later with reference to FIG. 9 described later.

In the foregoing description, the configuration in which the particles 5, 6 and the dispersion medium 4 are filled in the closed space formed in the space between the first substrate 1 and the second substrate 2 has been described. The particles 5 and 6 and the dispersion medium 4 may be encapsulated in a microcapsule, and the microcapsules may be stored in a space corresponding to the pixel.

EMBODIMENT OF THE INVENTION Below, it demonstrates more concretely based on the Example of this invention.

EXAMPLE 1

In this embodiment, an electrophoretic display device having an electrophoretic display element according to the first embodiment of the present invention shown in Figs. 1A and 1B is manufactured by the following production method. An electrophoretic display device includes a 600 x 1800 matrix panel. As shown in Fig. 7, the planar shape of the pixel is rectangular, and the pixel size is 40 mu m in width x 120 mu m in length.

First, using a 1.1 mm thick glass substrate as the first substrate 1, a thin film transistor TFT (not shown), IC (not shown), and wirings other than those required for driving are formed on the first substrate. After that, a Si ₃ N ₄ film is formed on the entire surface of the substrate as an insulating layer. Next, an Al layer is formed and patterned to form the first electrode 7. In addition, the TFT and the first electrode 7 are conducted through the contact holes formed in advance.

Next, after the first electrode 7 is formed, a white colored layer is formed by applying an acrylic resin to cover the entire surface of the first electrode 7, and the colored layer is formed of titanium oxide, alumina or the like. White pigments are dispersed on the first electrode (7).

Next, by the electroplating method, the second electrode 8 and the third electrode 9 constituting a part of the partition wall 3 are 10 mu m in height and width as the common electrode of each pixel as shown in FIG. It is formed at 5 μm. Thereafter, on the second electrode 8 and the third electrode 9, partition walls having a height of 7 m and a width of 5 m are formed to have a total (total) height of 17 m by the use of a thin film resist.

Next, a dispersion medium 4 of two types of black moving particles (first particle 5 and second particle 6) and isoparaffin (trade name: isopa (ISOPAR), manufactured by Exxon Corporation) was applied to each pixel. To charge. The dispersion medium 4 contains a charge control agent. The first particles 5 are positively charged, and the second particles 5 are negatively charged.

On the partition 4, the second substrate 2 is arranged, and the dispersion medium is sealed to complete the electrophoretic display element.

Next, the electrophoretic display element thus manufactured is connected to a drive driver (not shown) and the above-described first and second display operations are tested.

First, the first display operation will be described with reference to Figs. 1 (a) and 1 (b).

In this case, first, the first electrode 7 is set to 0V through the thin film transistor, and -10V and + 10V are applied to the second electrode 8 and the third electrode 9, which are common electrodes of all pixels, respectively, thereby providing the entire panel surface. Resets the pixel to the white state.

Next, a voltage of positive polarity corresponding to the gradation level is applied to the first electrode 7 via the thin film transistor, using the second electrode 8 and the third electrode 9 as a voltage of 0V. For example, in the case of black display, by applying + 10V, all negatively charged second particles 6 are distributed on the entire first electrode surface. In addition, in the case of gray scale display, the amount of the second particles 6 moving on the first electrode 7 is changed by changing the applied voltage such as 0 V, +2 V, +4 V, +6 V, +8 V, and the like.

Next, the second display operation will be described with reference to Figs. 2 (a) and 2 (b).

In this case, first, the voltage of the first electrode is set to 0V through the thin film transistor, and + 10V and -10V are applied to the second electrode 8 and the third electrode 9, respectively, to thereby make the pixels on the entire surface of the panel white. Reset to.

Next, a voltage of 0 V is applied to the second electrode 8 and the third electrode 9, and a voltage of negative polarity corresponding to a predetermined gradation level is applied to the first electrode 7 through the TFT. For example, in the case of black display, by applying -10V, all negatively charged second particles 6 are distributed on the entire first electrode surface. In the case of gradation display, the amount of the first particles 5 moving on the first electrode is changed by changing the applied voltage such as 0V, -2V, -4V, -6V, -8V.

The method of driving the matrix panel to be verified will be described with reference to Figs. 8A and 8B, which show 8x8 matrix panels for convenience of explanation. In Figs. 8A and 8B, each quadrangle corresponds to a pixel, in which? Denotes a first display operation, and? Denotes a second display operation.

In this embodiment, the display rewriting is performed by alternately repeating the display operation shown in Fig. 8A and the display operation shown in Fig. 8B. More specifically, the first display operation and the second display operation on the entire frame surface are alternately repeated while the first and second reset operations are performed therebetween, respectively. In this driving method, the polarity of the voltage applied in the pixel is changed and applied for each frame. Therefore, the frame inversion driving method is called.

Since the electrophoretic display device in this embodiment has the memory characteristic of the display state, in the case where the display state before the rewriting continues after the display rewriting, the display holding operation of applying 0 V to each electrode is performed. When the display state is sequentially changed like a moving picture, the above-mentioned frame inversion driving is repeated.

In this embodiment, according to the above driving method (frame inversion driving method), even when the display rewriting is repeated, reverse voltages are alternately applied to each electrode, so that the effective voltage can be approached to zero on average. As a result, it is possible to prevent the accumulation of residual DC components and to perform stable display rewriting with suppressed display burn-in.

EXAMPLE 2

In this embodiment, an electrophoretic display device having the electrophoretic display elements shown in Figs. 5A and 5B is manufactured by the following production method. The electrophoretic display device includes a 600 × 1800 matrix panel. In addition, as shown in FIG. 9, the planar shape of a pixel is a rectangle of 40 micrometers in width x 120 micrometers in length. In this embodiment, the electrode includes the first and second electrodes 71 and 81 as described above.

A thin film transistor (TFT) (not shown), IC (not shown), and wirings other than those required for driving are formed on a 1.1 mm thick glass substrate, which is the first substrate, and Si ₃ N is used as an insulating layer on the entire surface of the substrate. ₄ form a film. After that, an Al layer is formed and patterned to form the first electrode 71. In addition, the thin film transistor and the first electrode 71 are electrically connected through a contact hole formed in advance.

In addition, it is assumed that by forming irregularities on the surface of the first electrode, incident light is diffusely reflected to show white color.

Next, according to the electric field plating method, as shown in Fig. 9, the second electrode 81, which also functions as the partition wall 3, is formed to have a height of 10 mu m and a width of 5 mu m as a common electrode of each pixel. Subsequently, a barrier rib having a height of 7 μm and a width of 5 μm is further formed on the barrier rib formed by the second electrode 81 already formed, and the barrier rib 3 is formed to have a total height of 17 μm.

Next, each pixel is filled with two types of black moving particles (first particle 5, second particle 6) and ISO paraffin (trade name: Isopa, manufactured by Exxon). The charge control agent is contained in the dispersion medium 4. The 1st particle | grains 5 charge positively, and the 2nd particle | grains 6 charge negatively.

The electrophoretic particles and the dispersion medium satisfy the relationship between the relative dielectric constant of the electrophoretic particles> the relative dielectric constant of the dispersion medium, and the dielectric constant difference is 8 or more.

The second substrate is disposed on the partition wall and sealed to complete the electrophoretic display element.

Next, the electrophoretic display element thus produced is connected to a drive driver (not shown) and the above-described first and second display operations are verified.

First, the first display operation will be described with reference to Figs. 5 (a) and 5 (b).

In this case, a voltage of 0 V is supplied to the second electrode 81 which is the common electrode of all the pixels.

First, a sine wave of ± 15 V and a frequency of 1 kHz is applied to the first electrode 71 as an AC voltage through the TFT, and the pixel is reset to a white state.

Next, a voltage having a positive polarity corresponding to the predetermined gradation level is applied to the first electrode 71 through the TFT. For example, in the case of black display, by applying + 10V, all negatively charged second particles are distributed on the entire first electrode surface. In the case of gray scale display, the amount of the second particles moving on the first electrode is changed by performing voltage modulation such as 0 V, +2 V, +4 V, +6 V, +8 V, and the like.

Next, the second display operation will be described with reference to Figs. 6 (a) and 6 (b).

In this case, a voltage of 0 V is applied to the second electrode which is the common electrode of all the pixels.

First, a sine wave of ± 15 V and a frequency of 1 kHz is applied to the first electrode as an AC voltage through the TFT, and the pixel is reset to a white state.

Next, a negative polarity voltage corresponding to a predetermined gradation level is applied to the first electrode through the TFT. For example, in the case of black display, by applying + 10V, all of the negatively charged second particles 6 are distributed over the entire surface of the first electrode 71. In the case of gray scale display, voltage modulation such as 0V, -2V, -4V, -6V, -8V is performed, and the amount of the second (6) particles moving on the first electrode 71 is changed. .

Next, the verified method for driving the matrix panel will be described with reference to FIGS. 10A and 10B.

In this embodiment, the display rewriting is performed by alternately repeating the display operation shown in Fig. 10A and the display operation shown in Fig. 10B. More specifically, in the present embodiment, the first display operation and the second display operation are performed for each of two adjacent horizontal scanning lines, and the reset operation between the display operations shown in Figs. 8A and 8B is performed. In doing so, it repeats alternately. In this driving method, the polarity of the voltage applied in the pixel is changed for each scan line. Therefore, this driving method is called a line inversion driving method.

Since the electrophoretic display device of the present embodiment has memory characteristics with respect to the display state, in the case where the display of the previous display state is continued after the display rewriting, the display holding operation of applying 0 V to each electrode is performed. In the case where the display state is sequentially changed as in the video, the above-mentioned line inversion driving is repeated.

In this embodiment, according to the driving method (line inversion driving method), even when the display rewriting is repeated, reverse voltages are alternately applied to the first electrode 71, so that the effective voltage is set to zero on average. Can be close. As a result, accumulation of residual DC components can be prevented, and stable display rewriting with suppressed display burn-in can be performed.

EXAMPLE 3

In this embodiment, since it is the same as that of Example 2 except the verified method of driving a matrix panel, description of a manufacturing method and the like is omitted.

The driving method of the matrix panel to be verified will be described with reference to Figs. 11 (a) and 11 (b).

Here, for this embodiment, the display rewriting is repeated by alternately repeating the display operation shown in Fig. 10A and the display operation shown in Fig. 10B. More specifically, the first display operation and the second display operation are alternately repeated for each two adjacent pixels while performing the reset operation between the display operations shown in Figs. 8A and 8B. . In this driving method, the polarity of the voltage applied in the pixel is changed for each adjacent pixel. Therefore, it is called dot inversion driving method.

In the present embodiment, since the electrophoretic display apparatus has memory characteristics with respect to the display state, when the display state is continued after the display rewriting, the display holding operation of applying 0 V to each electrode is performed. When the display state such as a moving picture is changed sequentially, the dot inversion driving described above is repeated.

In the present embodiment, according to the above driving method (dot inversion), even when the display repetition is repeated, reverse voltages are alternately applied to the first electrode 71, so that the effective voltage approaches zero on average. Can be. As a result, it is possible to prevent the accumulation of residual DC components and to perform stable display rewriting in which display burn-in is suppressed.

Although the present invention has been described in connection with the structure disclosed herein, it is not limited to the details described, and this application is intended to cover the scope of the following claims or changes or modifications which may achieve the object of improvement.

According to the electrophoretic display device of the present invention, the electrophoretic display device can be driven by an AC voltage by using two kinds of electrophoretic particles having substantially the same color as different counter electrodes. In addition, when display or rewriting is repeated by alternately applying a display voltage of a predetermined polarity, a display voltage of a predetermined polarity and a display electrode of reverse polarity to a display electrode for displaying by changing the distribution state of the migrating particles. In addition, accumulation of residual DC components can be prevented, and stable display can be repeatedly performed.

Claims (12)

A first substrate having a sealed container; A pair of electrodes generating an electric field in a sealed container, Charged Particles Retained in a Closed Container As a display device, including The charged particles are moved by an electric field to determine the distribution of the charged particles in the sealed container, whereby displaying is performed, And the charged particles have different charging polarities and are composed of two kinds of substantially the same color. The method of claim 1, A display operation for forming the distribution of the charged particles by applying a voltage of a predetermined polarity to the pair of electrodes, and a distribution of the charged particles substantially by applying a voltage having an inverse polarity of the voltage of a predetermined polarity. And a display operation for alternately forming the same distribution. The method of claim 1, A display operation for forming the distribution of the charged particles by applying a voltage having a predetermined polarity after applying a reset voltage to reset the distribution of the charged particles, and reverse polarity of the reset voltage for resetting the distribution of the charged particles And a display operation for forming a distribution substantially equal to that of the charged particles by applying a voltage having a reverse polarity to a voltage having a predetermined polarity after applying the reset voltage. The method of claim 1, A second substrate disposed opposite the first substrate; A partition wall disposed between the first substrate and the second substrate to form a sealed container; A display electrode for distributing the charged particles dispersed in a first substrate or a second substrate; And a first reset electrode and a second reset electrode configured to collect two kinds of the charged particles and reset the display of the charged particles, respectively on one part and the other part of the partition wall. The method of claim 1, The apparatus includes a second substrate disposed opposite the first substrate; A partition wall disposed between the first substrate and the second substrate to form a sealed container; A display electrode for distributing the charged particles disposed on the first electrode or the second electrode; And a first electrode and a second electrode for collecting two kinds of the charged particles on the first electrode to reset the display of the charged particles. The method according to claim 4 or 5, The display electrode is a common electrode, the voltage of a predetermined polarity is a relative potential difference between the common electrode and one of the reset electrodes of the first and second reset electrodes, and is a display having a reverse polarity of the voltage of the predetermined polarity. And the voltage is a relative potential difference between the common electrode and the other reset electrode of the first reset electrode and the second reset electrode. The method of claim 1, And the sealed container is a microcapsule disposed between the first substrate and the second substrate. First and second substrates disposed at predetermined intervals to form a closed space; An electrophoretic display device comprising electrophoretic particles dispersed in the closed space, wherein the electrophoretic display device performs display by changing the distribution of the movable particles in the closed space. The apparatus further includes a display electrode for changing the distribution of the migrating particles for displaying, and a dispersion medium having a relative dielectric constant different from the migrating particles filled in the waste space and dispersed in the dispersion medium, The electrophoretic particles are electrophoretic particles having substantially the same color as the two different counter electrodes, and the display voltages having a reverse polarity are applied to the display electrodes alternately with a display voltage of a predetermined polarity and a voltage of the predetermined polarity. Electrophoretic display device characterized in that. The method of claim 8, The apparatus further comprises a reset electrode for collecting the phoretic particles and resetting the distribution of the phoretic particles, disposing a display electrode and a reset electrode such that a non-uniform electric field is formed therebetween, And an AC voltage is applied to the display electrode when the display is reset. The method of claim 9, When the relative dielectric constant of the electrophoretic particles is larger than the relative dielectric constant of the dispersion medium, the operation of moving the moving particles to a strong electric field region of non-uniform electric field distribution becomes a reset operation, and the relative dielectric constant of the electrophoretic particles is set to the specific dielectric constant of the dispersion medium. And when the permittivity is smaller than the permittivity, the operation of moving the moving particles to a weak electric field region of the non-uniform electric field distribution is a reset operation. A first substrate having a sealed container, two kinds of charged particles having substantially the same color as different counter electrodes and held in the sealed container, and an electrode for generating an electric field in the sealed container; A driving method of a display device in which particles are moved by an electric field to thereby determine a distribution of the charged particles in the hermetically sealed container, thereby performing display. Providing a display electrode for changing the distribution of the charged particles for displaying and a first and second reset electrode for changing the distribution of the charged particles for resetting the display; A first reset operation for resetting the display by applying a reset voltage of a predetermined polarity to the first and second reset electrodes, and a first display operation for displaying by applying a display voltage of a predetermined polarity to the display electrode; And a second reset operation for resetting the display by applying a reset voltage having a reverse polarity of the reset voltage of the predetermined polarity to the first and second reset electrodes, and a display voltage of the predetermined polarity to the display electrode. Repeating the second display operation for displaying by applying a display voltage having reverse polarity to Method of driving a display device comprising a. A first substrate and a second substrate arranged in a predetermined space to form a closed space, and a moving particle dispersed in the closed space, wherein the distribution state of the moving particles is changed in the closed space to display a display. As a drive driving method of an electrophoretic display device, A display electrode for changing the distribution of the migrating particles for performing the display, a reset electrode for changing the display reorganization of the migrating particles for resetting the display, and a non-distinct ratio of the migrating particles and being different from the phoretic particles. Providing a dispersion medium having a dielectric constant; A process using two kinds of electrophoretic particles having different counter electrode properties and having substantially the same color as the electrophoretic particles, Disposing the display electrode and the reset electrode such that a non-uniform electric field distribution is formed therebetween; A first display operation for displaying by applying a display voltage of a predetermined polarity to the display electrode, a reset operation for performing reset by applying an AC voltage to the display electrode, and an inverse of the display voltage of the predetermined polarity to the display electrode. Repeating the second display operation for displaying by applying the display voltage with polarity Method of driving an electrophoretic display device comprising a.

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